[Intel-gfx] [PATCH] drm/i915: Sleep and retry a GPU reset if at first we don't succeed

[Chris Wilson]

As we declare the GPU wedged if the reset fails, such a failure is quite
terminal. Before taking that drastic action, let's sleep first and try
active, in the hope that the hardware has quietened down and is then
able to reset. After a few such attempts, it is fair to say that the HW
is truly wedged.

References: https://bugs.freedesktop.org/show_bug.cgi?id=104007
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index e0f053f9c186..924ebe24b282 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1877,7 +1877,9 @@ void i915_reset(struct drm_i915_private *i915, unsigned int flags)
 {
 	struct i915_gpu_error *error = &i915->gpu_error;
 	int ret;
+	int i;
 
+	might_sleep();
 	lockdep_assert_held(&i915->drm.struct_mutex);
 	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &error->flags));
 
@@ -1900,12 +1902,20 @@ void i915_reset(struct drm_i915_private *i915, unsigned int flags)
 		goto error;
 	}
 
-	ret = intel_gpu_reset(i915, ALL_ENGINES);
-	if (ret) {
-		if (ret != -ENODEV)
-			DRM_ERROR("Failed to reset chip: %i\n", ret);
-		else
-			DRM_DEBUG_DRIVER("GPU reset disabled\n");
+	if (!intel_has_gpu_reset(i915)) {
+		DRM_DEBUG_DRIVER("GPU reset disabled\n");
+		goto error;
+	}
+
+	for (i = 0; i < 3; i++) {
+		ret = intel_gpu_reset(i915, ALL_ENGINES);
+		if (ret == 0)
+			break;
+
+		msleep(100);
+	}
+	if (ret != -ENODEV) {
+		DRM_ERROR("Failed to reset chip: %i\n", ret);
 		goto error;
 	}
 
-- 
2.15.1